The Familial and Social Ecology Module investigates the family, peer, social, and demographic factors that interact with, mediate or have main effects on substance use disorder (SUD) liability. Understanding SUD etiology requires determining how contextual factors (e.g. family, school, peers, neighborhood) interact with individual factors (e.g., temperament, cognition) to increase or reduce the risk for SUD. Thus, findings obtained from this module will guide the development of contextually specific and developmentally appropriate prevention programs that effectively reduce the risk for developing SUD. During the past decade, this module has undertaken a program of research to identify the factors contributing to transition from family to peer influence that bias the ontogenetic trajectory toward SUD. The research team consists of Drs. Blackson, Belsky, and Greenberg from the Department of Human Development and Family Studies at Penn State University; Dr. Heyman, (external consultant) from SUNY-Stoneybrook, and Dr. Ammerman, Co-investigator from Allegheny University of the Health Sciences. Dr. Kirisci, Director of CEDAR's Methodology and Statistical Core provides statistical expertise to this module. Dr. Linda Collins, Director of the Penn State NIDA-funded Methodology Center also serves as a statistical consultant.